As recognized today, organic compounds are the compounds formed primarily of carbon, hydrogen and oxygen, although other atoms such as nitrogen, sulfur and phosphorus may also be present. Inorganic chemistry essentially embraces all the compounds that are not organic compounds. In the natural world, organic compounds are found predominately in animal and vegetable matter, while minerals contain predominantly inorganic compounds. Over 90% of the earth's crust is composed of minerals, with silicate minerals, i.e., minerals having silicon-oxygen bonds, being by far the most prevalent.
While the natural world, and the historical development of chemistry, has tended to separate inorganic and organic compounds, modern researchers have become increasingly interested in preparing organic inorganic hybrid materials. As used herein, the term organic inorganic hybrid materials embraces two types of hybrids. In the first, covalent bonding occurs between an organic polymer and an inorganic matrix, and such hybrids will be referred to as covalent hybrids. An oxygen atom, which is commonly found in both organic polymers and inorganic matrices, is typically employed to link the organic and inorganic components of a covalent hybrid. In a second type of hybrid, the organic polymer and inorganic matrix are intimately mixed together, i.e., the organic polymer is uniformly dispersed throughout an inorganic matrix, or vice versa. This second type of hybrid, which does not contain a covalent bond between organic and inorganic components, will be referred to as dispersion hybrids. Covalent and dispersion hybrids are to be distinguished from conventional composite materials formed from organic and inorganic materials, where conventional composite materials have macroscopic interfaces.
The development of sol-gel chemistry, which occurred during the past two decades, has provided a convenient entry to the inorganic matrices of hybrid materials according to the invention. For leading references to sol-gel chemistry, which was initially developed for the preparation of ceramics, see, e.g., C. J. Brinker et al. Sol-Gel Science, The Physics and Chemistry of Sol-Gel Processing, Academic Press, San Diego (1990); D. R. Ulrich J. Non-Cryst. Solids (1990) 121:419; G. L. Wilkes et al., Silicon-Based Polymer Science, Advances in Chemistry Series 224, J. M. Ziegler and F. W. Fearon, Eds. Am. Chem. Soc., Washington, D.C. (1990), pp. 207-226; R. Dagani, Chemical & Engineering News (1991) 69-21:30; P. Calvert, Nature (1991) 353:501; and B. M. Novak, Adv. Mater. (1993) 5:422.
A number of organic polymers have been incorporated into SiO.sub.2 and/or TiO.sub.2 matrices. See, e.g., G. L. Wilkes et al., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) (1985) 26:300; H. Huang et al., Macromolecules (1987) 20:1322; J. E. Mark et al., Macromolecules (1984) 17:2613; J. E. Mark et al., Polymer (1985) 26:2069; S. B. Wang et al., Macromol. Reports (1991) A28:185; and Y. Haruvy et al., Chem. Mater. (1991) 3:501, using polydimethylsiloxane; H. Huang et al., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) (1985) 28:244, using poly(tetramethylene oxide); Nandi, et al., A. Chem. Mater. (1991) 3:201), using polyimides; B. Wang et al., Macromolecules (1991) 24:3449; and A. Morikawa et al., Polym. J. (1992) 24:107), using poly(arylene ether ketone) and poly(arylene ether sulfone); E. J. A. Pope et al., J. Mater. Res. (1989) 4:1018; C. J. T. Landry et al., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) (1991) 32:514; and N. W. Ellsworth et al., J. Am. Chem. Soc. (1991) 113:2756, using polymethacrylates; Y. Chujo et al., Macromolecules (1989) 22:2040; Y. Chujo et al., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) (1990) 31:59; and Y. Chujo et al., Makromol. Chem., Macromol. Symp. (1991) 42/43:303), using polyoxazolines. For reviews on specific applications of hybrid materials, see, e.g., M. G. Kanatzidls et al., Chem. & Eng. News (1990) 36; Handbook of Conducting Polymers, T. A. Skotheim, Ed. Marcel Dekker, New York (1986) 1 & 2; and ACS Symposium on Conducting Polymers: Polym. Prepr. (1994) 35-1.
Simultaneous with the development of sol-gel chemistry, and hybrid materials based on sol-gel chemistry, has been the development of conductive organic polymers, where that conductivity includes ionic and electronic conductivity. For representative reports describing electronically conductive organic polymers, see, e.g., Y. Wei et al., J. Polym Sci., Part A, Polym. Chem. (1989) 27: 2385-2396; Y. Wei et al., J. Polym Sci, Part-C (1990) 28:219-226; Y. Wei et al., J. Phys. Chem. (1990) 94:7716-7721; Y. Wei et al., Polym Prep. (1994) 35-1:242-243; Y. Wei et al., U.S. Pat. No. 4,940,517 (1990); Y. Wei et al., U.S. Pat. No. 4,986,886 (1991); and Y. Wei et al., U.S. Pat. No. 5,120,807 (1992).
For representative reports describing ionically conductive polymers, many of which are also used as ion exchange resins, see, e.g., Albright, R. L. and Yarnell, P. A., "Ion-Exchange Polymers" Encyclopedia of Polymer Science and Engineering, 2nd edition, 8:341-393 (1987); Inaba, M., et al., Chem. Lett. (1993) 10:1779; Rajamani, K., et al., J. Appl. Chem. Biotechnol. (1978) 28:699; Metwally, M. S., et al., J. Material Sci. (1990) 35:4993; Small, H., Ion Chromatography, Plenum Press, New York, (1989) pp. 41-55; Snyder, L. R., et al., Introduction to Modern Liquid Chromatography, 2nd edition, John Wiley & Sons, New York (1974); and Done, J. N., et al., Applications of High-Speed Liquid Chromatography, John Wiley & Sons, New York (1974).
Conductive polymers are being increasingly investigated for various commercial applications. For example, polyaniline has been studied as an electroactive coating that changes the corrosion behavior of stainless steel. See, e.g., DeBerry, D. W. J Electrochem. Soc., (1985) 132:1027. Designs for items containing conductive organic polymer often call for the polymer to adhere to inorganic materials, e.g., metal or ceramic. Achieving intimate and stable contact between a conductive organic polymer and an inorganic material has been problematic, and there remains a need in the art for methodology to achieve this goal.